Study On The Coupling Effect Of Piezoelectric Vibrators With High Electromechanical Properties

As a multifunctional material,the piezoelectric crystal material has a wide range of application in the fields such as medicine,industry.The relaxor ferroelectric single crystals,（1–x）Pb(Mg_1/3Nb_2/3)O₃-x Pb Ti O₃（PMN-PT）and（1–x）Pb(Zn_1/3Nb_2/3)O₃-x Pb Ti O₃（PZN-PT）,belong to a new type of piezoelectric crystal material,which exhibit superior electromechanical properties compared with traditional piezoelectric ceramics.In this paper,the size effect of PMN-PT（PMNT）and PZN-PT（PZNT）piezoelectric single crystal vibrators are researched.The effect of size on mode coupling and electromechanical coupling coefficient for single crystal vibrator is researched.Using mode coupling theory,for the PMNT and PZNT single crystals vibrators with different fractions in different polarization directions,the curves of relationship between the frequency constant f H and the arbitrary configuration ratio G are presented,and the electromechanical coupling coefficient and coupling coefficient are calculated.According to the obtained figures and data,the influence of size effect on mode coupling for the piezoelectric single crystal vibrator is analyzed.The temperature dependence of mode coupling effect and the electromechanical coupling coefficient for the piezoelectric vibrators polarized in[001]_cdirection with arbitrary configuration ratio is discussed.In this paper,the cylinder,cuboid and thin cylindrical shell piezoelectric vibrator models are established,the theoretical formulas of the three models are deduced,and the computer simulation calculation is carried out,and the frequency constants for the vibrators with arbitrary configuration ratio at different temperature are obtained.Using mode coupling theory,the coupling coefficients of the three kinds of piezoelectric vibrators at different temperature are calculated.At the same time,the frequency constant curves of the piezoelectric vibrators with arbitrary configuration ratio at different temperature are presented.The obtained parameters for cylinder,cuboid,and thin cylindrical shell models are compared,and the temperature dependence of the frequency constant and the mode dividing point is analyzed.Through simulation calculation,the electromechanical coupling coefficients of the cylindrical piezoelectric vibrator with arbitrary configuration ratio are calculated,and the relationship between temperature and the electromechanical coupling coefficient(k^eff),and that between temperature and the coupling coefficient （?） are found out.